Journal of Performance of Constructed Facilities

The City and County of Denver (CCD) Public Works Department owns, inspects, and maintains 531 bridges in its inventory of which 264 are considered major structures spanning over $6.1\mathrm{m}$ in length. In this paper, a methodology using the CCD major bridge network for the application of nondestructive evaluation (NDE) methods in bridge inspections is explained. The methodology, called Bridge Evaluation using Nondestructive Testing (BENT) helps systematically integrate NDE methods and conventional bridge management systems by using a Markovian deterioration model. Although the BENT method can be applied to timber, steel, and concrete bridges, in this paper the application of the method will be restricted to concrete bridges. The BENT system is part of a comprehensive geographic information system whereby database queries can be completed using a map interface. The database contains a wide array of information in the CCD infrastructure inventory including bridges, pavements, alleys, and street subsystems.

The Route 601 Bridge in Sugar Grove, Virginia, spans $11.89\mathrm{m}$ $\left(39\mathrm{ft}\right)$ over Dickey Creek. The bridge is the first to use the Strongwell $91.4\mathrm{cm}$ $\left(36\mathrm{in.}\right)$ deep fiber-reinforced polymer double web beam in a vehicular bridge superstructure. Construction of the new bridge was completed in October 2001 and field testing was undertaken shortly thereafter, as well as in June of 2002, to assess any potential changes in structural performance. This paper details the field evaluation of the Route 601 Bridge. Using midspan deflection and strain data from the October 2001 and June 2002 field tests, AASHTO bridge design parameters were determined—namely, wheel load distribution factor $g$ , dynamic load allowance $IM$ , and maximum deflection. The wheel load distribution factor was determined to be $S∕4$ , a dynamic load allowance was determined to be 0.36, and the maximum deflection of the bridge was $L∕\mathrm{1,110}$ . Deflection results were lower than the AASHTO $L∕800$ limit. This discrepancy is attributed to partial composite action of the deck-to-girder connections, bearing restraint at the supports, and contribution of guardrail stiffness. It was found that diaphragm removal had a small effect on the wheel load distribution factor.

A field study of corrosion of reinforcing bars in existing concrete pier structures is presented in this paper. The objective of the research was to evaluate the effectiveness of calcium nitrite for combating corrosion in marine structures. Five sites were selected for field evaluation of reinforcement corrosion in cooperation with the Harbors Division of the Hawaii Department of Transportation. The concrete for each of these sites included a calcium nitrite-based admixture as a corrosion inhibitor. Each site was tested for permeability, chloride ion concentration, half-cell potential, polarization resistance, and pH. Corrosion activity identified by half-cell potential measurements, polarization resistance measurements, and visual inspection of bars taken from cores indicated that high dosages of calcium nitrite, 19.8 to $22.3\mathrm{L}∕{\mathrm{m}}^3$ , provided the steel with significantly greater protection than lower dosages, $12.4\mathrm{L}∕{\mathrm{m}}^3$ . This occurred despite the fact that the sites with higher dosages were older and usually more permeable than the structures with lower dosages.

The Cape Hatteras Lighthouse is the tallest brick structure of its kind in the United States. The national icon was closed to visitors after several pieces of the cast iron stairs, original to the structure, dislodged and fell inside the lighthouse. This finding led to the investigative efforts outlined in this paper, on the load carrying capacity of the stairs. This article summarizes the engineering effort in the condition assessment of the stairs, the review of visitor statistical data for likely load exposures during peak times, and the development of a unique load test program for the stairs of the historic structure. The load testing program was unique because of the physical constraints of the lighthouse shaft as well as the dimensions of the stair treads. In addition, the engineering team had the added objective of protecting the integrity of the national icon and performing the load test without exposing the historic stairs to an unnecessary risk of failure.

This article discusses the use of nondestructive and laboratory testing techniques and load testing in evaluation of fire damage to precast prestressed concrete members in a parking structure. The in situ evaluation phase consisted of nondestructive testing of concrete using ultrasonic pulse velocity and radiographic exposures to locate tendons prior to the removal of cores. Flexural strength of concrete and dynamic Young’s modulus of elasticity and air permeability index of $25\mathrm{mm}$ $\left(1\mathrm{in.}\right)$ thick disks sawed from the cores were determined in the subsequent laboratory testing phase. Analysis of concrete properties at small depth increments permitted assessment of whether a damage gradient was present and the nature of any gradient found, as expressed by changes in these properties. Based on the compromise in material properties indicated by nondestructive and laboratory testing, two affected double-tees were load tested. The deflection pattern observed during load testing confirmed the compromise indicated by the findings of the testing program.

This paper presents an analysis of data from surface elevation surveys performed on 971 newly constructed posttensioned slabs-on-ground for single-family structures in California. The results of 1,368 manometer surveys were collected by the California Geotechnical Engineers Association (CGEA) and made available for this study. The parameters studied were maximum elevation differential, maximum elevation differential along the edges, maximum edge-to-interior differential, maximum local gradient, and local levelness $F_L$ number. In addition, data from 397 slabs surveyed both before tensioning and after tensioning/loading were analyzed. Results of the statistical analyses are presented in the form of histograms and cumulative frequency distribution curves, as well as in tabular form. The study showed that posttensioned slabs-on-ground for residential structures are not built level; they typically have some as-built elevation differentials and local gradients. If manometer surveys are made on newly constructed slabs, such as-built elevation differentials and surface gradients can be documented and distinguished from any long-term differentials or angular distortions that might occur because of postconstruction ground movement.

Corrosion rates of high chromium and conventional steel rebars were measured and compared by conducting two studies. One was on concrete blocks and the other was on bare steel rebars. In the former study, concrete blocks that had been made with two different steel rebars were placed in sodium chloride solutions, and air was blown through the solutions to accelerate corrosion of the embedded steel rebars. These blocks were taken out of the solution periodically, and the corrosion rates of the rebars were measured with a 3LP device. In the latter study, the bare rebars of the two steels were also corroded in sodium chloride solutions through which air was blown, withdrawn periodically, dried, and weighed after the corrosion products were removed. The corrosion rates were measured by the reduction of the weight of the rebars. In the study on concrete blocks, it was found that the corrosion rate increases for both steels as the concentration of sodium chloride in solution increases. It was also found that the corrosion rate of concrete blocks reinforced with conventional steel was about twice as much as that of the concrete blocks reinforced with high chromium steel after $132$ days of exposure. From the study on bare steel rebars, it was found that the rate of corrosion of conventional steel was 12 times as much as that of high chromium steel at 0.1% sodium chloride, and the ratio decreased to 2 times as much when the sodium chloride concentration was increased to 3%. It was also found that the corrosion rate of high chromium steel was very sensitive to sodium chloride concentrations whereas that of conventional steel was not sensitive. The corrosion products were analyzed using x-ray diffraction and atomic absorption spectroscopy to identify the minerals present in them. It was found that corrosion products produced on the high chromium steel were predominantly lepidocrocite $\left(\gamma \text{-}\mathrm{Fe}\mathrm{O}\mathrm{O}\mathrm{H}\right)$ and hematite $\left({\mathrm{Fe}}_2{\mathrm{O}}_3\right)$ , whereas that on the surface of conventional steel was predominantly magnetite $\left({\mathrm{Fe}}_3{\mathrm{O}}_4\right)$ . It appears that the former iron oxides form an adherent and nonporous protective layer while the latter iron oxides (magnetite) do not, which can explain the distinct difference in corrosion rates of the two steel rebars.

The international roughness index (IRI) is a measurement of pavement roughness that is widely accepted for evaluating pavement serviceability, especially its riding quality. Generally, as the age of pavement increases, its condition deteriorates and its IRI value increases. However, the IRI data collected from the Indiana highway system indicate that the IRI values vary considerably for similar pavements and traffic conditions at any given pavement age. This makes it difficult to establish the relationship between IRI and pavement age. In this study, the gray system theory was used to estimate the maximum, mean, and minimum IRI values at different pavement ages. It is believed that the three IRI values are essential for evaluating pavement serviceability. This paper presents the process of the gray system modeling for IRI estimation and discusses the effects of traffic volume on pavement roughness and the estimation accuracy of the gray system models.

The case of a hydroelectric power project is presented to show how lack of understanding and poor filter design, along with insufficient control of construction quality, caused the failure of a dam. This paper summarizes the forensic investigations and attempts to explain the conditions that led to the formation of sinkholes on the embankment slope and the subsequent initiation of progressive failure of the embankment. The steps necessary to restart the power project, including the final remedial design, are then detailed. This paper also discusses how the functions of various engineering design components are integrated in the context of failure of the embankment. This case serves as a lesson for practicing engineers concerning the difficult technical, professional, and procedural issues that may arise during the design and construction of critical infrastructures.

An effective method for combined environmental protection and structural restoration of wood piles in waterfront facilities is not available. The objective of the study presented in this paper is to survey the available methods for wood pile protection and structural restoration with the intent of developing an effective method. In addition to reviewing the available repair methods, a field inspection of a harbor in Maine was conducted to assess existing technologies. A wood pile repair method that utilizes bonded fiber-reinforced polymer (FRP) composite shells and a grouting material is proposed. Fiber, resin, adhesive, coating, and grouting materials are systematically analyzed to deliver the required system performance. Two fabrication methods for the FRP composite shells are discussed based on the experience gained in the fabrication of laboratory prototypes. Then a step-by-step procedure amenable for field installation is proposed, and a preliminary cost analysis is conducted to assess the feasibility of the proposed system.

Durable repairs of bridge piles exposed to a marine environment require a proper repair design, which includes understanding and preventing the deterioration mechanism in such environments and proper construction methods. To understand how repair systems work, it is important to recognize which deterioration mechanism the system prevents and controls. Conversely, to understand why a system does not work, one must determine the deterioration mechanisms that the system failed to control. The deterioration mechanism should be addressed before repair construction starts so that an appropriate solution can be achieved. Also, construction practices that accelerate deterioration mechanisms should be recognized and avoided. This paper describes efficient construction methods that can be incorporated in the construction of bridge pile repairs. It also gives recommendations to increase the life of a bridge pile repair by analyzing deterioration of repaired structures, defining the cause of deterioration, providing suggestions to enhance the performance of the repair by practical and feasible actions, and giving an integrated approach to bridge repair construction processes.